Hi all, I don’t post much but come on to have a read through the posts.
I have had a look through to see if this had been mentioned before but I’m unable to find anything related so I thought I would ask here before I raise a ticket.
I seem to be having issues with print quality in a certain area. I have tried different build plates, different speeds, temps, cooling, calibrations, flow etc but I continue to have this same issue. It happens at the front right corner nearest the door and sometimes the left corner too. My print seems to go very rough, almost like the nozzle is scrapping the print rather than laying down filament.
I do a few large prints so this isn’t ideal, some I can save with sanding but it’s time I would rather use elsewhere.
Has anyone come across this with there printer that could give me some other ideas as I’m totally out my depth now and the response times from support is crazy.
Hard to tell in the pictures, but looks like a classic case of the nozzle plowing because the part is warping / shifting / lifting as it gets higher - which makes sense around edges.
What’s the material being used here?
I’m betting the outer corners where this is occuring are taller (measuring with a set of calipers) than towards the middle of the print where it’s not.
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I also wonder if printing with some ears on the corners will help too.
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Do you type with the door closed? try printing deflectors on air ducts that direct the air flow 45 degrees upwards.
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Pics dont show it but I am guessing it is your sharp 90degree box corners on the enormous model causing it to pull up off the Sheet, or the sheet pulling up off the magnetic bed. Cold plates [IMO] tend to hold on, and its the magnetic part that fails first
Relieve those corners! mouse ears and or design change
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Hi,
I did think about it possibly lifting/warping but I can’t see any sign of this. I have tried it on both the standard and bq build plates and get the same issue either way. It only seems to be at the door area I run into this issue.
I was using sunlu pla+
Thanks
Hi,
The door was closed while printing. I did have deflectors on at one point and thought they might have been the issue so I removed them to see if it made any difference but unfortunately I seen no difference with then.
Thanks
Hi,
I did wonder if the actual plate could be lifting but that would need to be the case with both the standard plate and cold plate. I haven’t tried mouse ears but it was mentioned above so I will give that a go.
The prints I’m doing requires the large size, as I am fairly new to 3d printing do you have any suggestions on how to change the design in order to prevent this? I can’t alter the actual size, well I possibly could but this particular print is a two part print where both sections are the same size and joined using dowels.
Thanks
I will give this a try, just find it odd it’s only doing this at the door area and not at the rear inner corners too.
Thanks
It’s gotta be shifting something fierce. Just look at the corner and the amount of extra material being plowed all over the edge.
Think about it this way, your printer is going to glob material over the same coordinates over and over again while adjusting height if you are printing a rectangle of some sort.
So the printer keeps trying to print where it should but the model underneath it is slowly getting out of sync where those coordinates are being placed.
All those marks you see are called “plowing” because either the extruder is over-extruding something fierce (way too much material) or you are taking away the gap the material is supposed to be applied to because the model is moving around below it.
My guess would be the model moving around it. Just look at how uneven your square corner is and how it perpetually gets worse the higher it goes (more overhang).
You said you were newer to 3d printing. This is a classic case of the above. It’s probably happened to every single person that’s ever 3d printed. There’s many causes for it, but a good start would be to what others have said and trying to relieve some of the stress being caused by those extreme corners and thickness of the model.
Thanks for the quick response to my reply.
I’m assuming when you say try to remove some of the stress this is done by the mentioned above, using mouse ears?
I’m understanding what you are explaining but my thoughts process was why just that corner in particular although it has been know to be the opposite front corner or full front edge and not the inner rear corners. Again my thoughts process, would it not do this on all corners?
Again as I am new I’m not sure how else I can remove the stress from the print and ideally I don’t want to make the print any smaller as part of my reason for buying the printer was to print the large flat parts.
Any suggestions would be very welcome, thanks
I’d try first with the mouse ears/brim, sometimes a little help is all it needs
If it begins to lift up the plate or do other big shenanigans, you can consider adding small cutout veins like 0.2-1.0mm tall, in order to break up how big the “sheet of plastic is” at the bottom that is about to all cool as one big mass. Benchy bottom text sort of thing. I think hilbert curve is also specifically supposed to address this [stresses all directions] but I kinda hate it’s aesthetic lol.
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Thanks I’ll give it a try and look into what you mentioned, appreciate the reply 
I submitted a ticket with bambu and they gave me a few things to try, some I already had and one thing I hadn’t. The later being to manually adjust the bed level.
I have now done this and after that was complete I done a full calibration on the printer. I then ran another print similar to my previous one but I added mouse ears but unfortunately I got the same results once again, perhaps a worse result I would say. I then ran just a simple 60x60x8mm print in the corner I’m having issues in and it printed fine.
I have attached a couple of images to show the results of the larger print.
It’s still doing what I said earlier.
The difference here is you can really see more of the model since the golden/yellow color.
I’d say you are fighting 2 fronts, one being you need to calibrate your flow rate. It looks like you are pushing so much filament you are almost ironing while laying down your top layers which is pushing all that excessive filament over the edge.
As badly as we all want the top layer to be like glass, 3d printing perfect extrusion is not like glass in the horizontal. (why ironing exists to try to get it there).
You can clearly see it’s got so much extrusion that you can see both layers criss crossing each other in the middle. That is one of the reasons the model is probably shifting. The stress from excessive material.
When you measure the corner with a pair of calipers compared to measuring furthing in where it’s not plowing, how much height difference is there?
See what a “perfect’ish” extrusion should like like here:
Edit: Just as a quick test to comfirm, you can right click on the build plate and add a cube. Make it something simple like 15x15x15 and print it with your exact settings.
If you are extruding the right amount of filament, you should get all corners of that cube measuring the same (within a few thousandths) with a set of calipers. The edges should also look square and straight. I’m guessing the cube will show that you need to calibrate your filament.
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It’s a familiar picture, it was the same. I changed the nozzle to a new one (Perhaps there were remnants of the old filament ABS in it), and changed the PTFE tubes to tubes with a large inner diameter and slightly shortened the tube of the left nozzle to reduce bending (after that, the AMC began to feed the filament without difficulty, perhaps before that it was supplied jerkily). I do not know what exactly helped, but the situation improved. I also performed flow calibrations and all standard printer calibrations, including high temperature calibrations. I also washed the detergent plate very well and did not touch it with my bare hands. After carrying out all these procedures, I corrected the situation. Before that, I tried manual calibration of the platform and adjusting the height of the nozzle, nothing helped.
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Also, to test the theory with the material supply and dirty nozzle, try to print only with the right nozzle after washing the plate and calibrations.
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Why the problem only appears in front, then there may be 2 options, you always take the plate from the front, and the second, when the head is in these positions, the bending of the tube becomes critical and the filament disappears. Another test option is printing without AMS, feed the filament directly to the extruder
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Hi again and thanks for the reply. I’m actually away from home right now.
I will give this a check tomorrow but what I will say is I have done the flow calabration a few times now I’ve also done a manual bed leveling as bambu support suggested this which was out so I thought that was the issue, clearly not. I did run a print earlier that was the full length of the bed 50mm wide and 8mm high and it came out perfect, now I know that’s not proving much as it wasn’t as large as before but I wanted to try just that corner and up the edge where the cold air output was.
I will check with calipers tomorrow and let you know. My mind is telling me why just that corner
I totally understand what you are saying about it lifting/shifting but I’m wondering why just that corner. I had an idea that I could maybe somehow secure the plate to the bed in that corner but I’m not sure if that would even prove anything
Haven’t had a chance to check thickness of corners yet but I will check this later.
I did capture some pictures of the print I done yesterday which I have added. Having a think about this happening, could my bed temp be to cold? As you see I’m using a cool plate and I have noticed the pre-set temp is lower than usual.
Also I will print the 15x15x15 cube later, is there any particular place you recommend I print this on the plate?
